1. Field of the Invention
The present invention relates in general to booms employed in spraying agricultural crops and, more specifically, to support assemblies for mounting such booms on a portable frame.
2. Description of the Prior Art
Standard equipment presently employed for spraying chemical herbicides, pesticides or the like on agricultural crops includes a portable frame for carrying a chemical storage tank and a spray boom extended transversely adjacent one end of the frame. The spray boom has a plurality of spaced spray nozzles mounted thereon, and a pump and associated spray lines transfer the chemical from the storage tank to the spray nozzles.
To reduce the amount of time involved in spraying a field, long spray booms are being used that extend outwardly in cantilever fashion from opposite sides of the portable frame or vehicle on which they are mounted. A primary problem inherent in the use of spray booms of extreme length is that the rough terrain often encountered by the vehicles on which they are mounted subjects the booms to jarring or whipping forces that makes it difficult to stabilize the booms and maintain a uniform spraying pattern.
Various devices for mounting a boom to an implement have been employed to increase boom stability, such as those disclosed in U.S. Patents to Tangeman, U.S. Pat. No. 3,545,678 and Hugg, U.S. Pat. No. 4,039,147. The Tangeman reference discloses a boom stabilizing device that includes a pair of parallel link type systems for connecting a boom to an implement. Springs are connected between portions of the link systems, and the pivotal connections of the links forming the link systems include rubber bushings to provide a resilient support for the boom.
The Hugg reference also discloses the use of parallel link systems for mounting a boom to an implement in a stabilized manner. Thus, use of parallel link systems alone for mounting a spray boom is clearly old in the art, but such systems per se have not overcome objectionable sway and oscillatory movements of the boom.
The present invention relates in general to that of Tangeman in that it includes a pair of parallel link systems and coil springs for resiliently supporting the boom. However, in addition, shock absorbing means are provided to dampen oscillatory movement of the boom, and torsion members are fixed to and extend between the link systems to restrict horizontal tilting movement of the boom.